Hemophilus influenza type b is the most important cause of bacterial meningitis in children between the ages of 3 months and 4 years. The effect of bacterial meningitis in infants and young children can be severe and may include pyarthrosis, epiglottitis, maxillary sinusitis, ethmoid sinusitis, pneumonia and otitis media. Pyarthrosis in infants is difficult to diagnose and can lead to irreversible damage in the advanced lesion stage; epiglottitis can occur as a result of bacteremia and a tracheotomy is usually mandatory because of the high probability of sudden death as a result of respiratory or cardiac arrest; maxillary sinusitis may remain in a chronic condition for months if untreated while ethmoid sinusitis is very acute leading to periorbital cellulitis in one or both eyes. Pneumonia and otitis media can occur also as a consequence of nasopharyngeal involvement. The possibility of a synergistic effect of bacteria plus virus may exist and untreated cases may terminate fatally. Despite the effectiveness of certain antimicrobial therapy, no decline in mortality has been observed during the last decade to type b-induced meningitis while recovery from the disease has imposed a high percentage of neurological impairment. Clinically, there appears to be an increase in the number of infants under 2-3 months of age who are susceptible as well as in older children; increased adult susceptibility also may be a problem.